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9/16/2015
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Birth of a
Star
Latin for “cloud” “stellar nurseries”
Raw materials for stars
Explosions from old dying stars (supernova) trigger the power to create new stars.
Latin for “cloud”
“stellar nurseries”
Raw materials for stars
Explosions from old stars trigger the power to create new stars in these Nebulas.
Star
Power
the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus.
The hotter the star the more elements are made
Our Sun only can make Oxygen.
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Where did we get all our elements??
Scientist believe it’s made in the super hot, massive explosion – “Supernova”.
Energy is released from stars – Visible, UV, and IR
created by the transformation of hydrogeninto helium.
Star
Characteristics
Characteristics that
distinguish stars:
1. Temperature
2. Luminosity
3. Size
4. Life span
ALL OF THESE FACTORS
DEPEND ALMOST
ENTIRELY ON ONE
FACTOR…..
MASS
Temperature
• as objects are heated,
they start to glow
• stars of different colors
have different surface
temperatures
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Luminosity
• the amount of energy emitted
by a star in joules per second,
which are called watts
•W=J/s
Size
http://youtu.be/HEheh1BH34Q?hd=1
1.3 million Earths to fill up the Sun
Life Span
*Varies by Spectral Class
• Type O - < 2 Million years
• Type M - > 200 Billion years
Our Sun (G)~ 10 Billion years
It’s 4.5 billion years old now!
Star
Classifications
Remember...
“Oh Boy, A Fine
Girl Kissed Me”
Spectral classes of stars
Temperature & Color
• O - Deep Blue - >30,000 K (53540˚F)
• B - Blue - 20,000 K (35540˚F)
• A - White - 10,000 K (17540˚F)
• F - Yellow/White - 7,000 K (12140˚F)
• G - Yellow - 6,000 K (10340˚F)
• K - Orange - 4,000 K (6740˚F)
• M - Red - 3,000 K (4940˚F)
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The Hertzprung-Russell Diagram
(H-R Diagram)
plotted known stars
surface temperature (x-axis)
vs. luminosity (y-axis)
- Main Sequence Stars -(strip from top left to bottom right)
90% of stars. “Ordinary” Stars.
Our Sun is a main sequence star.
- White Dwarfs - (lower left)
small but hot. Very faint
- Supergiants - (top right) cool,
larger, and brighter
- Giants -
(upper right)
cool,
large stars. Very
bright.
Distribution
of
Stars
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•48 % of stars are single.
•36 % of stars are binary.
•12 % of stars in triple systems.
•4 % of stars are in quadruple
systems.
It turns out that most stars
are in multiple systems!Binary Star Systems
- size and orbit depends
on mass of stars
- 2 Stars physically linked to
one another by gravity
Death
Of a
Star
Our sun is predicted to gradually get bigger, brighter and cooler
It will become a Red Giant.
Then it will eventually become a white dwarf.
Very unlikely to go nova or supernovea
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Nova – large amounts of
material are dumped onto a white
dwarf igniting causing a sudden
enormous increase in brightness,
but then it slowly fades back to
its original luminosity. No
explosion.
Super Nova – occurs if the
mass of the white dwarf is
pushed over the Chandrasekhar
limit (1.4 solar masses).
Huge violent explosion!
can lead to the formation of successive
generation stars and planets (like ours)
We are made out of
Star Stuff!
-Neil Degrasse Tyson
